A biometric authentication technology has recently been developed for authenticating a device or system user using biometric information such as fingerprints and palm prints. With a biometric authentication device utilizing such a biometric authentication technology, biometric information about a user who wants to use the biometric authentication device is acquired as input biometric information. The input biometric information is verified against previously-registered biometric information about a previously-registered user(s), for example. If the biometric authentication device determines that the input biometric information coincides with the previously-registered biometric information, the user is authenticated as an authorized user based on the result of such a verification process. The biometric authentication device then gives permission to the authenticated user to use the biometric authentication device or any other device connected thereto.
Such a biometric authentication device is expected to reliably make available the previously-registered users for verification use. For the this purpose, there is a known technology of storing a history of previous verification results as verification information, and based on the verification information, determining an assessment threshold value for use as an assessment criterion for every verification assessment.
In addition to reliably making available the previously-registered users for verification, such a biometric authentication device is also considered desirable to complete a verification process in a short time. For not increasing the processing time needed for completion of a verification process, there is a known technology of making verification by pattern matching only when a first coincidence level found by characteristic-point matching is of a first threshold value or smaller and is of a second threshold value or larger, for example. Also for not increasing the processing time needed for completion of a verification process, there is another known technology of reducing the processing time for verification by using the quality of fingerprint data as a base to change how to make verification.
Patent Document 1: JP-A-7-121712
Patent Document 2: JP-A-2006-107340
Patent Document 3: JP-A-2007-213126